Driving mechanism for returning the roller of typewriters



J1me 1945- I. G. H. VON KRAEMER 2,378,520

DRIVING MECHANISM FOR RETURNING THE ROLLER OF TYPEWRITERS Filed Aug. 51, 1945 2 Sheets-Sheet l Ivan fius'huf Henn vow Kroeme IN an-ma Ki/o ATTY.

June 19, 19 5- I. G. H. VON KRAEMER I 2,378,520

DRIVING MECHANISM FOR RETURNING THE ROLLER OF TYPEWRITERS Filed Aug. 31, 1943 2 Sheets-Sheet 2 Fig. 4.

Patented June19, 1945 DRIVING MECHANISM FOR RETURNING THE ROLLER OF TYPEWRITEBS Ivan Gustaf Henry von Kraemer, Stockholm, Sweden Application August 31, 1943,, Serial No. 500,612

In Sweden March 3, 1942 4 Claims. (Cl. 197-66) When a person is engaged in type-writing he has to produce not only the intellectual performance of the writing itself but also to exert a physical work in the incessant moving back of the carriage for every line written. This is quite an unnecessary work which is eliminated by the present invention.

The present invention relates to a driving mechanism for returning the carriage of type-writers at the end of the written line.

According to the invention an electric motor is provided for winding up a spring which by means of a key is adapted to be connected to the carriage when the latter is to be returned. Moreover, there is a device for automatically connecting the motor to a. source of current when the spring has performed a certain work.

' shaft 2 or a motor I, which worm through a worm .wheel 4 and a toothed wheel 5 drives atoothed wheel 6, which is fixed to a casing I for a spiral spring 6 whose outer end is fixed to the casing 1 and whose inner end is fixed to the shaft 9, on which the casing I is freely mounted. To the wheel 6 there is fixed a sleeve l surrounding the shaft 6 and provided with two slots II, which by way of example may extend over about 90 of the periphery. On the lower threaded part of the shaft there is mounted a nut I 2 provided with proiections l3 entering into the said slots l I. Around the periphery of the nut there is a circular slot I 4 engaged by a fork l5 which is fixed to a two-armed lever l6, whose other end has the shape of a fork adapted to actuate the handle l8 of a switch l1.

At the upper part of the shaft 9 there is fixed a round disc l9.with axially directed bores 20 engage'd by pins 2| fixed in a disc 22 which is loosely mounted on the shaft 9. In a central bore 23 in partition 25 there are fixed two iron rings 28, 29,

coaxial with the shaft 9. -In the annular space between the rings there is provided an electrical winding 30. The driving disc 26 is connected to nected to the distribution system through conductors 36.

The operation of the device is as follows: When a line has been written on the typewriter, whether in full or only partly, and the carriage is to be returned, the key 34 is pressed down against the force of the spring 35, whereby current is supplied to the winding 30 which then produces a magnetic field, whose lines of force are closed through the driving disc 26 so that the said disc 26 is attracted and with its upper surface comes into contact with the disc 22. The magnetic'device'is so dimensioned that the attraction will be sumcient to overcome the force of the spring 24, so that the disc 22 is pressed upward and gets out of contact with the partition 25 and is stopped, by the disc l9 without the driving disc 26 coming into contact with the magnetic device 28, 29.

The space bar usually provided in type-writers is according to the present invention preferably divided into two parts, one of which, e. g., the left one, may constitute the returning key 34 and the other part serve as space bar so that these two keys are operated by the left and the right hand thumb respectively.

At the described movement of the discs 22 and 26 the friction has been transferred successively from the partition 25 to the driving disc 26,

If new the spring 8 has been sufiiciently wound up, it will, through the intermediary of the shaft 9, the disc IS, the pins 2| and the disc 22, rotate the driving disc 26 which then, by means of a cable (or steel band) attached'to the disc returns the carriage and actuates some suitable line shifting device, not shown. When the pressure on the key 34 ceases, the driving disc 26 falls down and thus comes out of contact with the disc 22, which by means of the spring 24 is now pressed against the partition 25 and thereby stopped. A braking device of some kind may be provided so as to lessen the speed of the carriage when it comesnear its, right end position. Also, the conductor 32 may pass over a contact controlled by the carriage and so arranged that the circuit is broken when the carriage comes near to its right end position.

When the current to the winding 30 has been switched off by releasing the key 34 and the driving disc 26 consequently has been disconnected in the manner described above, writing may take place. During the writing the cable will cause the driving'disc to turn a small angle at each step of the carriage. The spiral spring 3| serves to keep the cable tight and to turn the driving disc back if the carriage is returned by hand.

At the above described rotation of the shaft 9 this shaft will screw the nut l2 down, whereby the nut l2 actuates the switch l1 through the lever I6. When a number of lines have been written so that the nut has come down to a certain point, the switch l'I-which preferably is a quick-closing and quick-breaking one--is closed and the motor starts and drives through the worm gear 3, 4 and the gear 5, 6, the spring casing 1 so that the spring is wound up. At the same time the sleeve l9, which is fixed to the toothed wheel 6, will turn the nut I2, so that it is screwed up on the shaft 9 until it has been moved so much as to open the switch by means of the lever l6 whereby the motor stops. It is also possible, as shown in Fig. 5, to make the partition axially displaceable instead of the driving disc. The winding 30a may, for this purpose, be arranged on a circular iron ring 3% secured to the casing, the left part of this ring being shown'in section in Fig. 5. The partition 25a is axially movable and is acted upon by the winding 30a against the action of springs 30c distributed along the periphery of ring 30b, one of said springs being shown in Fig. 5. The winding 30a is energized in the same manner as described with respect to Fig. 1.. The partition 25a is secured against rotation by means of one or more pins 30d fixed in the ring 30b and passing through suitable holes provided in the partition 25a.

The device according to Figure 2 differs from the device according to Figure 1 fundamentally thereby that the electric control of the driving disc has been replaced by manual control and that the nut, which actuates the switch, is driven through gears so that its displacement for each line is less than that according to Figure 1.

When the carriage is to be returned, the key 3| is pressed down against the action of the spring 35 and thereby actuates the link 3 and the lever 342, which is mounted at 343 and by means of a fork with pins engages a circular slot 26l in the driving disc 26, which is thereby pressed against the disc 22! and will press the same down against the action of the spring 24 so that the disc 22l loses its contact with the partition 25. The outer end of the spring 8 will then turn the spring casing I and thereby, through the pins ll fixed to the spring casing I will turn the gear 12 and thereby the screw 13 so that the nut l2! threaded thereon is screwed down and actuates the push button I12 of the switch I'll. When a number of lines have been written, so that the push button l12'has been displaced a certain distance, the switch is closed. Thereby the motor I is started and rotates the shaft 9 through the worm gear 3, l, the gear 5 and the gear 6| which is fixed on the shaft 9, at which the inner end of the spring 8 is fixed, so that the spring 8 is wound up. At the same time the shaft drives the gear 92 through the gear 9! fixed on the 13, until the spring-actuated push button I12 has shaft 9 so that the pins 92! fixed in the gear 92 and engaging bores in the nut I2l will rotate the. said nut I2l, thereby screwing it up on the screw risen so much that the circuit is opened and the motor is stopped.

The device according to Figures 3 and 4 differs from the device according to Figure 2 only concerning the actuating of the switch. On the shaft 2 of the motor I thereis slidably mounted a worm 3! provided with a slot ill. A pin 2H] fixed in the shaft 2 is displaceable in the slot 3 and serves to cause the worm to rotate with the shaft. A spring 3l2 presses a slide 3l3 against the worm, the said slide being prevented from rotating by means of a stop or guide not shown. The slide 3 is provided with two projections 3 serving to operate a switch I13, as will be described below. The worm 3H) drives a worm gear 4|, which by means of a gear 5l0, H0 drives the shaft 9, to which the spring 8 is fixed. For the rest the device is identical with the device according to Figure 2.

As is easily understood, the force exerted by the worm gear 4| on the worm 3") in the axial direction of the latter is proportional to the force of the spring 8. Consequently, when a number of lines have been written so that the spring 8 has become sufiiciently slack, the spring 3i2 has successively expanded and has displaced the slide 3l3 to the left so that the right projection 3M closes the switch H3. The motor is now started and is loading ,the spring 8 through the gears 8N, 4| and H0, BIO, thereby increasing the torque of the spring 8 and thus com-pressing the spring 3l2. When the spring 8 has been wholly wound up, the left projection 3 will open the switch I13 whereby the motor is stopped.

Having now described my invention, what I 40 claim as new and desire to secure by Letters Patent is:

1. Driving mechanism for returning the carriage oi typewriters, comprising the combination of a driving spiral spring for returning the carriage, means for winding said spring connected to one end of said spring, a member connected to the other end of the spring and normally in engagement with a non-rotatable part, a freely mounted driving disc adapted to be connected to the carriage, and manually operable means to bring the driving disc into engagement with the said member and to bring this member out of engagement with the non-rotatable part, to allow said driving spring to drive said driving disc.

2. Driving mechanism according to claim 1. including a shaft to which said other end of the driving spring is connected a disc fixed on said shaft, a second disc mounted on said shaft for rotation with and axially displaceable relative to said first disc, said second disc being resiliently urged against a non-rotatable plate, an electromagnet provided on this plate, a key controlled switch for connecting said electromagnet to a current source, said driving disc consisting of magnetisable material and being freely mounted on the shaft, the said electromagnet, when magnetised, serving to bring the driving disc into engagement with the said second disc and to bring said second disc out of engagement with the nonrotatable plate to allow said driving spring to drive said driving disc.

3. Driving mechanism according to claim 1, including a casing for said driving spring, said other end of said driving spring being fixed to said casing, a disc rotatable with and axially displaceable relative to said casing, said disc being 4. Driving mechanism according to claim 1, resiliently urged against a non-rotatable plate, including a key adapted to displace the non-roand a key adapted, when pressed down, to press tatable part in order to disengage it from the the driving disc against the said displaceable disc member connected to the driving spring and and thereby to bring the latter out of contact 5 thereby to bring the said member into engagewith the non-rotatable plate to allow said driving ment with the driving disc.

spring to drive said driving disc. IVAN GUSTAF HENRY VON KRAEMER. 

